1. Field of the Invention
The present invention relates to an information playback apparatus and information playback method for playing back contents stored in an information storage medium.
2. Description of the Related Art
In recent years, the standard for a read-only DVD (Digital Versatile Disk) has been specified, and playback apparatus that play back video/audio information stored in read-only DVDs are commercially available.
According to the read-only DVD standard, the read-only DVD stores presentation data which records actual video and audio data, and navigation data used to manage the presentation data. The presentation data contains video data, audio data, and sub-picture data, which are multiplexed according to the specification of a program stream (2048 bytes) specified by MPEG2. The navigation data describes PGCs (ProGram Chains) and Cells, which set a time configuration and order of video and audio data to be played back. With this navigation data, multi-angle, multi-story, and parental functions can be implemented.
As a prior art associated with the above technique, an image display apparatus which provides a service that integrates a DVD-Video title and HTML file has been disclosed in Jpn. Pat. Appln. KOKAI Publication No. 11-161663. This image display apparatus extracts a URL from a navigation pack in a video object unit, and establishes connection to the Internet based on the extracted URL, so as to display data in conjunction with a scene to be played back.
According to the read-only DVD standard, only an MPEG2 program stream recorded on a disk can be played back, and information other than the MPEG2 program stream recorded on the disk cannot be played back. That is, the expandability of DVD playback is poor.
In general, the readout speed of information from a DVD is higher than the download speed of information via the Internet. That is, a given period of time is required to download information via the Internet, thus producing a certain wait time for the user. In order to solve this problem, a method of downloading all pieces of necessary information via the Internet, and then starting playback may be used. However, this method requires a large-capacity buffer for downloading, resulting an increase in cost of the apparatus.